Add benchmark results for multiple Nostr relay backends

Introduced comprehensive benchmarks for `next-orly-badger`, `next-orly-neo4j`, and `nostr-rs-relay` backends, covering peak throughput, burst patterns, mixed read/write, query, and concurrent query/store tests. Reports include detailed performance metrics (e.g., events/sec, latency, success rates) and are saved as text and AsciiDoc formats. Aggregate summary also generated for testing consistency across relay implementations.

cmd/benchmark/.claude/settings.local.json

@@ -0,0 +1,9 @@
+{
+  "permissions": {
+    "allow": [
+      "Bash(ls:*)"
+    ],
+    "deny": [],
+    "ask": []
+  }
+}